The present disclosure is generally directed to techniques in the field of telecommunications.
With advent of the Internet and mobile telephone technologies, new and different types of services become available to consumers. In addition to making simple cellular phone calls, more and more mobile phone subscribers are using their mobile devices for services such as GPS, texting, multimedia streaming, searching, and others. To provide these services, service providers and various standard bodies have come up with different types of architectures and systems.
One of these systems is called IP Multimedia Subsystem or IP Multimedia Core Network Subsystem (IMS), which is an architectural framework for delivering Internet Protocol (IP) multimedia services. For example, the IMS architecture is described online by, among other sources, the Wikipedia (see http://en.wikipedia.org/wiki/IP Multimedia Subsystem). It was originally designed by the wireless standards body 3rd Generation Partnership Project (3GPP), as a part of the vision for evolving mobile networks beyond GSM. Its original formulation (3GPP Rel-5) represented an approach to delivering “Internet services” over GPRS. This vision was later updated by 3GPP 3GPP2 and ETSI TISPAN by requiring support of networks other than GPRS, such as Wireless LAN, CDMA2000 and fixed line.
To ease the integration with the Internet, IMS uses IETF protocols wherever possible, e.g., Session Initiation Protocol (SIP). According to the 3GPP, IMS is not intended to standardize applications but rather to aid the access of multimedia and voice applications from wireless and wireline terminals, i.e. create a form of fixed-mobile convergence (FMC). This is done by having a horizontal control layer that isolates the access network from the service layer. From a logical architecture perspective, services need not have their own control functions, as the control layer is a common horizontal layer. However, in implementation this does not necessarily map into greater reduced cost and complexity.